[clang] [clang-tools-extra] [analyzer] Remove alpha.core.IdenticalExpr Checker (PR #114715)

[Balazs Benics via cfe-commits]

steakhal wrote:

I'm pretty sure last time I've compared this checker to the tidy implementation, I saw slight differences.
Have you thoroughly compared the two? Have you seen discrepancies?

Speaking of the tests, I'd also prefer migrating existing ones to uncover differences.
Unfortunately, frequently our test coverage is not great and because of that I don't think we can drop this unless we/you do a through comparison of the two.

BTW I'm all in favor of reducing code duplication, and clang-tidy is a much better place for this rule.

https://github.com/llvm/llvm-project/pull/114715